In my Australian Application No. 82234/82, Pat. No. 552107 entitled SPRAYING MEANS AND METHOD, there was described means whereby very low volume but high concentrate spraying could be effected. The contents of the specification, claims and drawings of that said patent comprise the closest prior art known to the Applicant.
There are many applications for such spraying devices, including a requirement to be able to spray at high speed over terrain with a minimum of loss due to wind effects. One example of such a requirement is the spraying of weeds alongside a railroad track. It is known to be desirable to avoid the growth of weeds in the ballast itself, since such growth can cause accumulation of sand or dirt, but on the other hand it is desirable that the weeds be allowed to persist at the shoulders of the ballast, in order to inhibit the drift of sand or dust.
This requirement has been well recognised and it is common practice to spray weeds solely on the ballast with a dilute solution of weedicide drawn by a locomotive. However the costs of drawing very large quantities of water for the weedicide solution is very high and the main object of this invention is to provide an improvement whereby such costs can be considerably reduced, and whereby high concentrate low volume spraying can be incorporated.
However the difficulty which has been encountered heretofore has been the tendency for such spraying to be displaced by natural air turbulence, side winds and the like, since high concentration low volume spraying necessarily involves small droplet size. Another object of this invention is to provide means whereby such turbulence or side winds will have much less effect than heretofore and thereby the spraying can be more effective.